This invention is directed to systems and devices for measuring or detecting small gaps between metal objects.
Various devices and techniques for detecting or measuring small gaps between objects, such as metal contacts in a switch, are known. For example, the well-known micrometer is such a device for measuring small but visible distances between objects. Another example of a known device is the dielectric tester. Use of this type of tester is effective for determining the presence of gaps that are not visible, but typically destroys the article being tested. The dielectric tester can only determine whether or not a gap is sufficient for a particular purpose, but cannot determine the width of the gap.
Thus, neither the known micrometer nor the known dielectric tester can measure gaps that are not visible without destroying the article being tested.
The present invention includes a system and method for measuring and/or detecting gaps or distances that are non-visible (defined as either enclosed or otherwise obscured, or too small to be seen by the naked eye) and making such measurements without destroying the article being tested.
The present invention comprises a system having an RF signal generator having an output interface that outputs an RF signal and that interfaces with an input portion of a test device that is electrically connected with a first surface of a gap. The system also comprises an RF signal receiver having an input interface that receives an RF signal and that interfaces with an output portion of the test device that is electrically connected with a second surface of the gap. The RF signal receiver generates an electrical output to an output interface when an RF signal is detected. A processor has an input interface that interfaces with the output interface of the RF signal receiver and the processor converts the electrical signal from the receiver into an indication to the user of the presence of the gap in the test device.
Thus, according to the present invention, an RF signal is applied to one side of a suspected gap in a test object. An RF receiver is connected to the other side of the suspected gap. For example, for a metal test object, such as a switch, the signal is applied to one contact and the receiver is connected to the other.
If no gap exists, then the capacitance of the gap is a maximum, and the RF signal received by the receiver will be its strongest. (This will be referred to as the "baseline" signal for a particular test device.) On the other hand, as the gap increases in size, its capacitance decreases, and the received signal decreases in amplitude with respect to the baseline signal.
The electrical signal outputted by the receiver is proportional to the strength of the RF signal received, and thus will also decrease from a maximum (corresponding to the baseline signal) as the gap size increases. Thus, the electrical output of the receiver correlates to the width of the gap.
The electrical signal outputted by the receiver is processed using standard amplification and other digital processing devices. For example, the output of the processing may be made to detect a gap exceeding a certain threshold, which would correspond to the received RF signal dropping to an amplitude such that the electrical signal generated by the receiver fell below a threshold level, as determined by the processing.
Alternatively, two or more known gaps in the test device may be used to correlate the received RF signal to known gap widths in a test device. These calibration points may be used with the processing to generate an output of gap width for the test devices.